the link you give describes a test where you go hard for 10 minuets followed by going hard for another 20 and taking the average HR for the 20. i know they don't mention it but all this hard work probably touches your max HR.
i "climbed" the radio tower twice on Monday and my max was only 150, almost 20 from my observed. for me i think my max happens just after i die on a sprint or kill myself going up a short but steep hill. for the same ride it was 153 up the hill after the KOM in reverse.